Resting-state functional connectivity and socioemotional processes in male perpetrators of intimate partner violence against women

Intimate partner violence against women (IPVAW) is a serious and overwhelming public concern. Neuroimaging techniques have provided insights into the brain mechanisms underlying IPVAW perpetration. The purpose of this study is to examine the resting-state functional connectivity (rsFC) involving the process of social decision-making of male perpetrators. Twenty-six male perpetrators convicted for an IPVAW crime were compared to 29 men convicted for crimes other than IPVAW (other offenders) and 29 men with no criminal records (non-offenders) using a seed-based approach. Seeds were located in areas involved in reflective (prefrontal), impulsive (amygdala and striatum) and interoceptive (insula) processing. Then, as an exploratory analysis, the connectivity networks on male perpetrators were correlated with measures of executive functions and socioemotional self-report measures. Male perpetrators in comparison to other offenders and non-offenders, presented higher rsFC between prefrontal, limbic, brainstem, temporal and basal ganglia areas. Also male perpetrators showed higher rsFC between insula, default mode network and basal ganglia, while lower rsFC was found between prefrontal and motor areas and between amygdala, occipital and parietal areas. Exploratory correlations suggest that the specific rsFC in male perpetrators might be more related to socioemotional processes than to executive functions. These results showed that male perpetrators present a specific rsFC in brain systems that are essential for an adaptive social decision-making.

The Spanish version of the Emotional Regulation Questionnaire [5]. It is a 10-item scale designed to measure the capacity to regulate emotions through two processes: cognitive reappraisal (6 items) and expressive suppression (4 items). Participants answer on a 7-point Likert scale ranging from 1 "strongly disagree" to 7 "strongly agree".
For our subsequent correlational analyses, we used the total score of each of the questionnaires explained above except for the emotional regulation questionnaire (ERQ), where cognitive reappraisal and expressive suppression were considered as two different dependent variables.

Executive functions assessment
Four components of executive functioning were measured based in a previous study [6]. These four components were selected based on prior literature, where differences in male perpetrator were found [7].
Updating process: the letter-number sequencing [8] was used. Participants were asked to repeat a combination of an increasingly longer list of numbers and letters by organizing the numbers in ascending order and the letters in alphabetical order. The total number of correct answers was used as an index of updating ability.
Response inhibition: a go/no go task was employed using a tablet-based task of 100 trials divided into 4 blocks. In the first 50 trials (1° and 2° blocks), participants were asked to press a key as quickly as possible when the GO stimulus was presented (a black figure of a bear) and to inhibit the response for the NO-GO trials (a black figure of a dolphin). Then, participants hear a bell and have to change their response from the GO to the NO-GO stimulus for the next 50 trials (3° and 4° blocks). Thus, participants were asked to press the key when the NO-GO stimulus appeared and to inhibit the answer for the GO trials. The interstimulus interval (ISI) was established in 1.000ms, and each stimulus was presented for 500ms. The score resulting from the subtraction of the 3° block and the 2° block was used as an indirect measure of response inhibition.
Decision making: a computerized version of the Iowa Gambling Task [9] was used. This task involved four decks of cards (A, B, C and D). Participants were told to choose one card at a time from one of the 4 decks and after each choice, they received an economic reward and in some cases they also received an economic punishment. A and B decks were disadvantageous because even if they produced higher immediate gains they also resulted in higher punishment points. C and D decks were advantageous, because they resulted in modest rewards but lower punishment. In the long run, choosing from the advantageous decks would yield more money and less punishment. The variable was first calculated by subtracting the number of disadvantageous choices from the advantageous choices for each block (5 blocks of 20 trials). Then, a sum of all blocks' results was computed and used as an indirect decisionmaking proxy.
Cognitive flexibility: due to technical problems, instead of using the Trail Making Test as in the previous study [6] with male perpetrators, we selected the arrow-version of the Spatial Stroop task [10].
Participants were asked to respond to the left/right direction of an arrow regardless of its left/right position on a tablet screen. On congruent trials, the direction in which the arrow pointed was consistent with its location (right pointing arrow located in the right side, or left pointing arrow located in the left side). On incongruent trials, the arrow's direction was opposite to its location (right pointing arrow located in the left side or left pointing arrow located in the right side). The attentional cost variable was taken as an indirect measure of cognitive flexibility. It was calculated by subtracting the reaction time of the change-trials (when a trial is preceded by a different trial) from the first-repetition-trials (when a trial is preceded by the same trial).
Impulsivity: for this purpose, we selected the Spanish short version of the Impulsive Behavior Scale [11].
It consists of 20 items that measure 5 impulsivity traits: negative, urgency, lack of premeditation, lack of perseverance, sensation of seeking and positive urgency. The items are scored on a 4-point Likert Scale ranging from 1 "strongly agree" to 4 "strongly disagree". The higher the score, the higher the impulsivity. We used the total score of the scale as a measure of impulsivity trait for the correlational analysis.

Supplemental File 2. Seed Selection and Generation
The selection of the seeds was built on the Triadic Reflective-Impulsive-Interoceptive Awareness Model of Turel and Bechara [12]. This neurocognitive model was created to study the basis of problematic behaviors. It is based on the premise that there are three differentiated but dependent systems that play a crucial role in decision-making: The Impulsive amygdala-striatal brain system which mediates the generation of impulses to act headfirst in order to obtain incentive rewards and it is also important to form habituated and automatic behaviors [13]. Second, the Reflective prefrontal brain system, which is thought to be involved in executive functions such as working toward a defined goal, uses conscious reflections, manages predictions and expectation of outcomes and is involved in social control [14].
Finally, the Interoceptive-awareness insular brain system is implicated in perceiving, processing and representing afferent internal bodily signals [15], essential for a functional social behavior. As a result, in this first step, we selected 4 main areas from which final seeds would be generated: amygdala, prefrontal area and striatum and insula. Within the impulsive system, amygdala was divided into: centromedial amygdala (rCMA and lCMA) and basolateral amygdala (rBLA and lBLA) regions according to its cytoarchitectonic characteristics ( [16]. We chose from the striatum, the ventral striatum (VS). Both rVS and lVS masks involved the lateralized ventral caudate (VSi) and nucleus accumbens (VSs), directly related to the rewarding process.
Local maxima coordinates were obtained from the article Functional Connectivity of Human Striatum: A Resting State fMRI Study [17]. The amygdala-striatal seeds were located using a 3.5-mm-radius spheres. Within the reflective system, the prefrontal cortex was divided into: medial prefrontal cortex (MPFC), bilateral dorsolateral prefrontal cortex (rDLPFC and lDLPFC) and bilateral ventrolateral prefrontal cortex (rVLPFC and lVLPFC) [18,19]. The mean activity of each prefrontal seed was extracted from a 6-mm-radius sphere. Finally, within the interoceptive-awareness system, the insula was divided in left and right anterior (AI) and posterior insula (PI), based on the assumption that each one belongs to dissociable resting-state networks [20]. Insula' seeds were located using a 2-mmradius spheres. In total, 15 seed were generated in MNI stereotaxic space using the MarsBar toolbox for SPM12 (http://marsbar.sourceforge.net).  * Even though these results appear to be contradictory, it might be explained by the model upon which each scale is based. Concretely, DERS scale [21] is based on a clinical-contextual model of emotional regulation and therefore focuses on presumed trait-level abilities. By contrast, ERQ questionnaire [22] was created from an affective science-based framework and attended to processes related to emotional regulation [23].

SEEDS FWHM (mm) Minimum cluster size
Supplemental Figure 1. Significant Pearson partial correlation between seeds' functional connectivity and executive functions and socioemotional processes in MPG